Television system



Sept. 25, 1934.

J. WEINBERGER ET AL TELEVISION SYSTEM Filed March 25, 1929 2Sheets-Sheet l JWEINBEKGER T. R SMITH BY on m /l/m/bL/- ATTORNEYTELEVISION SYSTEM Filed March25. 1929 2 Sheets-Sheet INVENTORS onwemenamTASMITH G. DWlN TT'OR EY Patented Sept. 25, 1934 UNITE STATES TELEVISIONSYSTEM Julius YVeinberger,

New

VYork, N. Y., Theo-A dore A. Smith, Ridgewood, N. J., and George Rodwin,New York, N. Y., assignors to Radio Corporation of America, acorporationofDela- WareV Application March 25,

2 Claims.

The present -invention relates to television Vsystems and moreparticularly to television systems in which the picture signal, speechsignal, and a synchronizing signal are all simultaneouslyl transmittedWithina frequency band of a predetermined width.

As was disclosed by copending application of Alfred N. GoldsmithandwJulius Weinberger, in application Serial 190,349,652, led March 25,1929, now Patent No. 1,770,205, of July 8, 1930, it has been found mostpracticalwith the present commercial developments of various types' oftelevision apparatus to transmit a synchronizing frequencysimultaneously `with the television picture signal so that propersynchronization between the transmitter and receiver may be continuallymaintained, and the need for constantly framing the received picture bymanual means avoided.

Also, in connection with television transmission, it is particularlydesirable in many cases to transmit speech or music accompanying theaction simultaneously with the picture. Particular application of thesimultaneous transmission of speech and picture signals is found in thetransmission of moving picture lms Where it is customary in the presentdevelopmentsrof the moving picture art to produce a sound recordaccompanying the film. l

Therefore, one of the objects of the present invention is to provide amethod and arrangement by which the transmission of the televisionpicture impulses, the speechsignals, and the synchronizing frequency isaccomplished simultaneously. y

Still a further object of our invention is to provide a system whereinthe picture signals, the speech signals, and the synchronizing frequencymay be transmittedsimultaneously within a predetermined frequency band'of minimum. width for commercial application, which, for example, hasbeen illustrated as being of a width of 100 kilocycles.

Still another object of our invention is to provide a system whereintheV synchronizing frequency is produced as a beat note in contrast togenerating a higher frequency suitable ,for synchronizing.

Still another object of our-invention is to provide a method andarrangement whereby the incoming signals are amplified to alarge-extent, while they are still of superaudible character so thatlittle, if any, amplification maybe necessary after these signals havebeen properly filtered for discriminatingY between each-'of the three vabove named types of signals,

1929,L Serial No. 349,834 (c1. '17a- 6) Other and ancillaryobjects ofour invention will at once suggest themselves to those skilled in theart to which the invention relates by reading the followingspecification in connection with the accompanying drawings, wherein:

Fig. '1 shows diagrammatica'lly an arrangement of the location of theparticular frequencies chosen by Way of vexample so that the televisionpicture signals, the speech signals, and the synchronizing signals mayall be confined within a frequency band of apredetermined width; and, vFig. 2 conventionally illustrates in a diagrammatic manner one form oftransmitter arrangement for accomplishing the above named results; and,

Fig. 3 diagrammatically and conventionally illustrates a form ofreceiving apparatus which may be used in conjunction with thetransmitter arrangement of Fig, 2.

Now making reference to the accompanying drawings, and, in particular,Fig. 1 thereof, it will be noted that 'an arrangement has been disclosedwherein the television signals are spaced over 80 kilocycles of the 100kilocycleband, and the speech signals are clustered about a carrierfrequency removed by 53 kilocycles from the television carrier, andextend over a 10 kilocycle band in the usual manner for broadcast work.The synchronizing frequencies have been chosen as being of k1.2kilocycles wide, and arranged so as to appear as side-bands located 6.4kilocycles on either side of the speech and vsynchronizing carrierVfrequency, and, as shown, are 1.2 kilocycles Wide.. Y n Y For thepurpose of 'giving concrete examples of the particularchosen,carrierfrequencieawe haveherein illustrated the same by specificexamples, Vand byY applying suitablefvalues to veach carrier and to eachfrequency band, although it is to be recognized that many changes mayherein be Vmade'without departing from the spirit and scope 'of 'theinvention, and that all values of frequencies illustrated herein are tobe regarded as merely illustrative and not limiting.

Now referring more particularly to Fig. 2 of the-drawings, furtherexplanationv of the diagrammatic arrangement of the various carriersshown in Fig. 1 will be'apparent. In Fig. 2, we have arranged a speechinput amplifier 1, for example ofQth'e type disclosed' by Arnold PatentNo. 1,329,283, dated January V2'7'1', 1920, as capable of carryingspeech frequencies varying between zero and5000cycles, and theV outputof this amplier is' directed to an audio ampliiier 3, which may be', ofthe same type as the above named vGili Arnold patent, as willhereinafter be described, is for amplifying both the speech and thesynchronizing frequencies.

It has been found suitable in some commercial work in connection withtelevision apparatus to synchronize from the 60 cycle A. C.

mains, but in cases where the receiver` is located in a different cityfrom the transmitter, the power line frequency is apt to vary andunsatisfactory results, so far as the synchronizing of televisionapparatus is concerned, are produced. Therefore, we have provided anarrangement wherein the 60 cycle frequency supplied in the city wherethe transmitter is located may be used for synchronizing apparatus, andby the aid of a frequency multiplier 5, such as has been disclosed byKendall Patent No. 1,446,752, dated February 27, 1923, we have raisedthis frequency to one of the harmonics of 60 cycles, and, asillustrated, have chosen to supply 600 cycles as a synchronizingfrequency. While not shown on the illustration, this may readily beproduced by biasing a vacuum tube fed with 60'cycle A.C. energy andtuning the plate circuit to 600 cycles, or, in other words, by adistortedamplie-r in which the output thereof is tuned to one of theharmonics of the impressed frequency.

The 600 cycle energy used for synchronizing may then be directed throughan audio amplifier 7 of the type disclosed for the amplifier 3 forexample, preferably of a highly regenerative type, which may be providedto act as an additional filter for the purpose of selecting the ,600cycle note, and also function as a high gain amplifier. Also located atthe transmitter, we have provided an oscillator 9 generating a frequencyof 6400 cycles, for example, which has been shown as a suitablefrequency for producing the 600 cycle synchronizing tone as a beat notein the receiver, and this 6400 cycle generated tone is then modulated inthe balanced modulator 1l, such as is disclosed by Hartley Patent No.1,571,006 of January 26, 1926, by means of the 600 cycle Ytone producedas a harmonic of the 60 cycles, so that the output of the balancedmodulator 11 contains frequencies of 5800, 6400 and 7000 cycles, whichmay then be amplined through an audio amplifier 13 of any well knowntype such as is disclosed by Arnold Patent No. 1,329,283 above named.The output from the audio amplifier 13 is then directedv to the `audioamplifier 3 already containing the speech input frequencies varyingbetween zero and .5000 cycles so that the combined audio output from theamplifier 3 contains both speech and synchronizing signals which vary infrequency between zero and 7000 cycles. The output from this .amplifieris then directed through a modulator 15 of any well known type disclosedby Heising Patent No. 1,442,146 of January 16, 1923 arranged formodulating both the speech andsynchronizing signals varying between zeroand 7000 cycles.

A radio frequency oscillator Y17 of the well known Hartley type, forexample, such as is disclosed by Hartley Patent No. 1,356,763, datedOctober 26, 1920, has been provided for the 'purpose of generating acarrier frequency suitable for the speech and synchronizing signals,Vand a portion of the output of this oscillator, which, as herein shown,has been chosenV as a 2007 kilocycle oscillator, is directed through aradio frequency amplifier 19, such as that 'disclosed by AlexandersonPatent No. 1,173,079, dated February 22, 1916, where it is modulated bymeans of -the speech and synchronizing signals varying between zero and7000 kilocycles so that the output of the radio frequency amplier 19contains the 2007 kilocycle frequency plus or minus frequencies varyingbetween zero and 7 kilocycles, which will be transmitted as rthe speechand synchronizing signals.

Television signals produced by means of scanning the subject which is tobetransmitted, such as, for example, a person seated in front of thetelevisor, moving picture nlm, or even an outdoor scene, have beenchosen as varying between zero and 40,000 cycles, and these signals arethen amplified through an amplifier 2l of well known type such as isshown for example by Arnold Patent No. 1,129,942 of March 2, 1915 inconnection with television apparatus, and the output thereof is arrangedto pass through a low pass filter 23 of well known type such, forexample, as that disclosed by Campbell Patent No. 1,227,113, dated May22, 1917, arranged to pass all signals of frequencies between zero and40,000 cycles with a cut-off point at 40,000 cycles. These signals arethen directed through a modulator 25 as shown for example by NelsonPatent No. 1,349,729, dated August 17, 1920, which also passes signalsvarying between zero and 40,000 cycles.

.4s a generator of the carrier frequency for the television signal, Wehave provided an oscillator 27 of the type disclosed by Nelson PatentNo. 1,349,729, dated August 17, 1920, whose frequency has been chosen as53y kilocycles, for example, and this frequency is arranged to modulatethe 2007 kilocycle frequency of the radio frequency oscillator 17 so asto produce in the balanced modulator 29, of the same general type asthat disclosed by Hartley Patent No. 1,571,006, above named, outputfrequencies of 1954, 2007 and 2060 kilocycles. The output of thebalanced modulator 29 is preferably tuned so as to pass the carrierfrequency of 2060 kilocycles. This energy is then directed through asingle frequency lter 31, for example such as that disclosed byAlexanderson Patent No. 1,173,079, above named, tuned to the 2060kilocycle carrier which is then passed to the radioI frequency amplifier33 which is preferably of the type disclosed in the last namedAlexanderson patent, where it is modulated by the television signalsvarying between zero and 40,000 cycles, so that the output of'amplifier33 contains the frequency 2060 kilocycles,i

plus or minus frequencies varying between zero and 40 lrilocycles, whichmay then be transmitted as a television signal.

Now referring to Fig. 3 showing a receiver system suitable for use inconnection with the transmitter of Fig. 2, we have shown aradiofrequency amplifier' 35 such as that disclosed by Alexanderson PatentNo. 1,173,079, which receives the television signal varying from zero to40 kilocycles on either side of the 2060 kilocycle carrier frequency,and speech and synchronizing s'ignais,l

which is supplied a locally generated frequency of J 1850 kilocyclesgenerated in the local oscillator 39 which is preferably of the sametype of oscillator as the oscillator 17 of the transmitter, so that theoutput from the frequency changer 37 appearing in the intermediatefrequencyv amplifier 41 `apiis L mining the television signal.

'i amplifier 49, of the type pears as frequencies of 210 kilocycles,plus or minus frequencies varyingv between zero and 40' kilocycles, and157 kilocycles, plus or minus zero to 7 kilocycles. The intermediatefrequency ampliiier 41, preferably of the type disclosed by above namedArmstrong Patent No. 1,342,885, is tuned to pass a frequency band lyingbetween 150 and 250 kilocycles. It is important to herein note that thetelevision signals, as well as the speech and synchronizing signals, areamplified to a large extent in this intermediate frequency ampliiier 41so that the need of amplification to any high degree after the separatesignals have been vseparated one from the other is unnecessary. By

the term intermediate frequency we mean a frequency which liesintermediate a radio frequency and a second generated frequency which isused to modulate the radio frequency. It is known that in every radiofrequency transmitter there is generated a radio frequency carrier andone or more modulation frequencies, such as voice signals, picture ortelevision signals, or the like, to modulate this radio frequencycarrier, and an intermediate frequency is any frequency which liesbetween these two and which appears at the receiver but does not existat the transmitter. In other words, an intermediate frequency receiveris one which is characterized by the fact that there is developedlocally in the receiver appara- "i tus a frequency lying in the rangebetween the received radio frequency and the range of the frequencyfinally detected and serving to actuate an electro-optical orelectro-acoustic device.

After amplification to the desired extent in the intermediate frequencyamplifier 41, it is necessary to select the individual signals, such asthe television signal, the speed signal and the synchronizing signal,and these various signals may be selected by means of band pass filters43 'l and 45, each preferably of the type disclosed by Whittle et al.Patent No. 1,714,149, dated May 21, 1929, in which the band pass filter43, for eX- ample, is tuned to frequencies varying between 170 and 250kilocycles for the purpose of deter- The output from the band passfilter 43 is then detected in the in- Y termediate frequency detector 47as disclosed by Armstrong Patent No. 1,342,885, so that the outputthereof appears as frequencies varying be- "g tween zero and 40kilocycles, which were the original television signals appearing in theaudio amplifier 21. These frequencies varying between zero and 40kilocycles are then amplified to whatever extent is found necessary bymeans of the ent No. 1,129,742, above named, and used for the purpose ofproducing a glow in the television lamp 51 which may be of the usualneon, helium or argon type, well known in the art to which this j;invention relates.

The television lamp 51 is then arranged behind the disk 53, assumingthat a disk is used for the purpose of rebuilding the television image,so that a person looking at the disk from the right of the showing ofFig. 3 will see the lamp behind the various holes inthe disk, and thedisclosed by Arnold Pat-y signals is avoided to a material extent.Output energy from the band pass filter is then directed through anintermediate frequency detector 55, similar to the intermediatefrequency detector 47, so that the output thereof appears as signals offrequency varying between zero and 7 kilocycles, and then by passingthese signals through the audio frequency amplifier 57 of the typedisclosed by Arnold Patent No. 1,329,283 of January 27, 1920, for thepurpose of further amplifying the same, signals of a strength sufficient'to produce a good indication in the loud speaker or a largesynchronizing torque on the synchronizing device are obtained. f

For the purpose of reproducing the speed signals, we have provided a nowpass filter 59 of the Campbell type, such as has been disclosed byCampbell Patent No. 1,227,113, Vdated May 22, 1917, tuned to passsignals of a frequency below 5000 cycles, and connected the same to theoutput of the audio frequency amplifier 57, and connected a loud speaker61 or other similar device to the output of the filter 59 so as toproduce an audible indication at the receiver of the sound impulsesproduced at the transmitter.

Also connected to the output of the audio frequency amplifier 57, wehave arranged a second band pass filter 63 which is preferablyconstructed in accordance with the teachings of Whittle et al. PatentNo. 1,714,149, dated May 21, 1929 tunedto pass signals of frequenciesvarying between 5300 and 7000 cycles which will be used as thesynchronizing signal, and, by means of a detector amplifier 65,preferably constructed in accordance with the combined teachings ofAlexanderson and Arnold as disclosed in their respective Patents Nos.1,173,079 and 1,129,942 are able to produce as an output thereof,signals of a frequency of 600 cycles which may then be applied to drivea synchronous motor or other appropriate synchronous mechanism 67located at the receiver. The synchronous motor 67, as shown, isconnected with the main shaft of a power motor 69, which may be eitherof the A. C. or D. C. type for driving the disk 53, and by means of thesynchronous motor 67, the torque exerted on the power motor 69 eitherserves to retard or advance the motor speed, and thus keep the disk insynchronism with a similar element at the transmitting station.

As a modification of the above described arl rangement, we may, wheredesired, utilize only a single side band for the television signal and aslight variation in the arrangement of all frequencies in thetransmitted band. For example, s

can be employedv and thus give better picture y detail. One side band ofthe modulated television carrier may then be filtered out by suitablemeans. In thel case illustrated, the lower side band will be filteredout and thus leave the television carrier of 2029 kilocycles with asingle side band extending from 2020 kilocycles to 2100.

kilocycles. l

In the last mentioned illustration, the receiver arrangement may remainunchanged from the form illustrated, with the exception that the 1amplifier following the television intermediate frequency detectorshould be arranged to pass zero to 80,000 cycles.

While we have herein illustrated concrete examples of the variousfrequencies chosen for the H CAD purpose of illustration, Vit is to benoted that these are merely suggested so as to give a clearer idea ofthe arrangement, and We believe ourselves entitled to make allmodications and changes in the present system such as Would readilysuggest themselves to one skilled in the art to Which the inventionrelates, provided, of course, all such modifications and changes fallfairly Within the spirit and scope of the present invention as dened bythe hereinafter appended claims.

Having now described our invention, what We claim and desire to secureby Letters Patent is the following:

l. The method of receiving television signals wherein the signalsinclude a wide band of frequencies and are composed of image, speech andsynchronizing signals wherein a relatively large portion of the entirefrequency band is occupied by image signals, a small portion is occupiedby speech signals, and a minute portion is occupied by synchronizingsignals, which comprises picking up at the receiving point the combinedimage, speech and synchronizing signals, amplifying all the signals,generating at the point of reception a local frequency, beating allincoming signals With the locally produced frequency to produce anintermediate beat frequency representative of all signals received,amplifying the produced intermediate beat frequencies to substantiallythe fullest extent desired as intermediate frequencies, filtering theintermediate frequencies to select in one group image signals and in asecond group speech and synchronizing signals, detecting each of thefiltered band of frequencies, producing from the detected image signalsthe visible indications, filtering from the detected synchronizing andspeech signals two independent signals, and producing from the filteredand separated speech and synchronizing signals sound effects and framingeffects of the produced visible signais.

2. A television receiving method for receiving jointly transmitted imageand synchronizing signals to coordinate the image signals to properlocations when the image signals are reproduced as electro-optical imagerepresentations which comprises the steps of receiving the image and,

synchronizing signals, amplifying both signals in a common amplier,locally generating signals, beating the locally generated with thereceived signals to produce intermediate frequency signals therefrom,amplifying the resulting beat frequency signals of intermediatefrequency value to substantially the full extent While the signals arein the frequency range of the produced intermediate frequenoy,separating the amplified intermediate frequency image signals from thesynchronizing signals, detecting each of the separated frequenciesproducing electro-optical detected image representations from the imagesignals, and locating the points at Which the produced imagerepresentations are observable by the detected synchronizing signals.

JULIUS VEINBERGER. THEODORE A. SMITH. GEORGE RODWIN.

